Multidimensional Modulation Of P3ht/Perovskite Interface by Aromatic Ring Dicarboxylic Acid Small Molecules for Highly Efficient and Stable Perovskite Solar Cells

Abstract

Poly(3-hexylthiophene) (P3HT), a dopant-free hole transport material for perovskite solar cell, offers scalability and thermal stability but suffers from poor interfacial adhesion and defect-induced recombination at the perovskite interface. To address these challenges, this study introduces two aromatic dicarboxylic acid small molecules, 4-carboxyphenylacetic acid (4-CPA) and phenylene diacetic acid (Phl(OAc)₂), for multidimensional modulation of the perovskite/P3HT interface. Theoretical calculations reveal that the dual carboxyl groups in these molecules enable dual-site passivation of undercoordinated Pb2+ defects on the perovskite surface, while their aromatic rings induce π-π stacking with P3HT, optimizing molecular orientation and charge transport. Experimental results demonstrate significant performance enhancements: power conversion efficiency of 4-CPA- and Phl(OAc)2-modified devices increased from 12.04% (control) to 19.90% and 21.48%, respectively. Moreover, the modified perovskite films exhibit superior hydrophobicity, retaining stable perovskite phases after 7 days in high humidity (55–65% RH), whereas the control decomposes into PbI2. Unencapsulated devices maintain 89% and 90% of their initial PCE after 2400 hours under low humidity (15% RH), highlighting exceptional long-term stability. This work provides a robust interfacial engineering strategy for advancing efficient and stable PSCs toward practical applications.

Keywords: Perovskite solar cells, P3HT,  Interface engineering,  Multidimensional modulation.